MiR-135a-3p inhibits the progression of prostate cancer by targeting TLR4

Abstract

To explore the expression of miR-135a-3p in prostate cancer，analyze its effects on tumor development and the involved mechanisms. A total of 125 specimens of cancer tissues and corresponding adjacent normal tissues from prostate cancer patients were collected. Real - Time quantitative PCR was employed to quantify the expression levels of miR-135a-3p in prostate cancer tissues and cell lines. Kaplan-Meier survival curve analysis and Cox regression were performed to evaluate the prognostic significance of miR-135a-3p in prostate cancer. The CCK-8 assay was used to detect cell proliferation. A dual-luciferase reporter assay was employed to validate the targeting interaction between miR-135a-3p and Toll-like receptor 4 (TLR4). miR-135a-3p is lowly expressed in prostate cancer tissues and cells, and its low expression is associated with poor prognosis of patients. The low expression state of miR-135a-3p showed a significant correlation with TNM stage, clinical stage, Gleason score, and lymph node metastasis. In addition, miR-135a-3p inhibits the proliferation of prostate cancer cells and cancer progression by negatively regulating the expression of TLR4. miR-135a-3p is downregulated in prostate cancer and is associated with poor prognosis of patients. It exerts an inhibitory effect on the progression of prostate cancer by targeting TLR4.

Keywords: Prostate cancer; TLR4; miR-135a-3p; prognosis.

Figure 1.

miR-135a-3p expression and prostate cancer prognosis. The expression of miR-135a-3p in tumor tissues of prostate cancer patients was significantly lower than that in adjacent tissues (p < .001) (A). The survival time of patients with low expression of miR-135a-3p is significantly shorter than that of patients with high expression of miR-135a-3p (log-rank p = .012) (B). *** P＜0.001.

Figure 2.

Effect of miR-135a-3p on proliferation of prostate cancer cells. The expression level of miR-135a-3p in prostate cancer cell lines was significantly lower than that in normal prostate epithelial cells (p < .01). Among these prostate cancer cell lines, the expression levels of miR-135a-3p in PC3 and DU145 cells were relatively low (p < .001) (A). RT-qPCR is used to detect the expression of miR-135a-3p to verify the transfection efficiency (B). The CCK-8 assay was used to detect the effect of miR-135a-3p expression on cell proliferation (C-D). **P＜0.01, *** P＜0.001.

Figure 3.

The targeting relationship between miR-135a-3p and TLR4. The potential binding sites between miR-135a-3p and TLR4 (A). The luciferase reporter gene assay was used to further verify the targeting relationship (B-C). The expression level of TLR4 mRNA in prostate cancer tissues was markedly upregulated compared to adjacent normal tissues (p < .001) (2743i” ia_version=“0” > D). The expression levels of miR-135a-3p and TLR4 in prostate cancer tissues (r = −0.797, p < .001) (E). In the PC3 and DU145 cell lines, miR-135a-3p targets and regulates the expression of TLR4 (F). * P＜0.05, **P＜0.01, *** P＜0.001.

Figure 4.

Effect of miR-135a-3p targeting TLR4 on proliferation of prostate cancer cells. RT-qPCR was used to detect the relative expression levels of miR-135a-3p and TLR4 after transfection/co-transfection. The CCK8 assay is used to detect the proliferation of cells after transfection/co-transfection (A-C: PC3 cells, D-F: are DU145 cells). ns, P＞0.05, **P＜0.01, *** P＜0.001.